Pitman connection



June 1958 w. G. MILLEl 2,837,357

PITMAN CONNECTION Filed March 29, 1955 INVE/V 7012; William g. k/llz'llez PITMAN CONNECTION William G. Miller, Toronto, Ontario, Canada, assignor to Massey-Harris-Ferguson Inc., Racine, Wis., a company of Maryland Application March 29, 1955, Serial No. 497,742

1 Claim. (Cl. 287-89) This invention relates to cutting mechanisms of the reciprocating knife type such as are employed in agricultural machines, for example, mowers and harvesters. More specifically, this invention is directed to an improved quick release means for connecting the knife head to the pitman.

An object of this invention is to provide a pitman having a novel quick release connecting means for attachment to a reciprocable knife head.

Another object of this invention is to provide a pitman for translating rotary motion into reciprocatory motion having pivotable clamping arms which arequickly and positively disengageable from the knife head and which have a spring biased cam member for securely holding them in engagement with said knife head.

Another object of this invention is to provide a pitman having swingable clamping arms lockable to a knife head and also having a cam member which quickly and positively unlocks said arms by a simple lever movement; the cam member being spring biased to hold the arms in locking position relative to the knife head and automatically compensating for any wear or looseness therebetween.

Other objects and advantages of this invention will become more apparent as this disclosure progresses, reference being had to the accompanying drawings in which:

Figure l is a plan view, partially in section, showing the improved pitman and its associated parts.

Figure 2 is a plan view of the cam member and its actuating lever as shown in Figure 1.

Figure 3 is an elevational view, partially in section, of the arrangement shown in Figure 1.

Figure 4 is an exploded view of the actuating lever, cam member and their connecting lost motion link.

Referring more particularly to thedrawings, the rotary member is mounted on a shaft (not shown) in its bore 12 and is driven by a V-belt (not shown) trained around in the groove 14 on its periphery., The rotary member 10 acts as a flywheel and has a mass section 16 on one side of its center which counterbalances the opposite side 17 to which the pitman 20 is connected. A shaft 22 is mounted within side 17 and extends outwardly therefrom. A hub 24 is rotatably mounted on shaft 22 by means of anti-friction bearings (not shown) and has a portion 26 integral therewith. A pin 28 extends through a bore in portion 26 and has secured to either of its extending ends, the bifurcated ends 30, 31 of yoke 32. The bifurcated ends 30, 31 are split at 34 and are securely tightened on shaft 28 by the cap bolts 35, 36, respectively, which freely extend through the free ends 37, 38 of yoke 32 and are threadably engaged in the yoke 32 proper. The pitman 20 is thus free to swing rearwardly about shaft 28 as indicated by the arrow in Figure 1, upon becoming detached from the machine proper, in the well known manner, when an obstruction is encountered by the knife.

The knife head 40 comprises a horizontally disposed plate 41 having an upstanding web portion 42 to the up States Patent ICC per end of which is secured a connector in the form of a ball 44. To the plate 41 is connected the conventional reciprocable knife bar (not shown).

Tubular rod 46 is welded to yoke 32 at 47 and threads are tapped in its other end 48 for engagement with the threaded end 50 of pitman member 52. A lock nut 53 prevents any relative movement between the pitman members 46 and 52. The member 52 is bifurcated and comprises side portions. 54, 56 each having at its free end a bore through which extend pins 58, 60, respectively. Pivotally secured on pins 58, 60 are the clamping arms 62, 64 and for this purpose their bifurcated inner ends 66, 68 have apertures which receive pins 58, 60. Between the bifurcated ends of each arm 62, 64 and integral therewith are pitman releasing projections 70, 71 having releasing surfaces 73, 74 engageable with a cam means to be described. The outer ends of arms 62, 64

have socket portions with complementary concave surfaces 76, "77 facing each other which form a socket for connector 44 when in the operative or engaged position. Surfaces 76, 77 are formed as portions of a sphere and form a close, smooth fitting connection with the ballshaped connector 44. The arms 62, 64 thus swing between a position in which they lock about connector 44 and a position in which they release the connector and are completely clear of it for easy removal. It is between surfaces 76, 77 and connector 44 that wear and misalignment often occur in a connection of this type. Twisting moments of the knife head, and the high accelerative forces, which are a maximum at each end of the stroke, contribute greatly to the punishment taken by such a connection. As a result, looseness in this connection has been of considerable concern, because, once started, the condition quickly becomes aggravated. Also between the bifurcations of arms 62, 64, and integral therewith, are locking surfaces 80, 81 respectively, which are forced towards each other, by means to be described, to tightly clamp the spherical surfaces 7 6, '77 of arms 62, 64 on the connector or ball 44 as arms 62, 64 pivot about their respective pins 58, 60.

Extending from pitman portion 52 are spaced lugs 84, each having an aperture extending therethrough and in registry with an aperture 83 in lever 87 which is rotatably mounted intermediate its length between lugs 84, 85 on a shaft 86 extending through the aligned apertures. The lower bifurcated end 88 of lever 87 extends between side portions 54, 56 and has an aperture 89 which receives pin 90 to which is pivotally connected, by its aperture 91, link 92. Link 92 has therein a slot 93 for the reception of pin 94, slidable therein, to which is pivoted the bifurcated end 95 of cam member 96. The other end of cam member 96 is of U shape and has cam locking surfaces 97, 98 engageable with locking surfaces 80, 81 of arms 62, 64. As cam member is shifted to the right, as viewed in the drawings, the arms 62, 64 lock about connector 44 as previously described.

Link 92 has an aperture 99 in which is secured a plug 100. A compression spring 102 is positioned over link 92 and one end bears against a washer 104 abutted against plug 100. The other end of spring 102 bears against shoulders 105, 106 of cam member 96 and acts to urge it against locking surfaces 80, 81 with the result that spherical surfaces 76, 77 firmly embrace the ball. The various parts are so adjusted that pin 94 never bears against the extreme end 108 of slot 93 when in the locking or operative position. Therefore, the arms 62, 64 are alwaysin firm engagement with connector 44 re gardless of the wear which may have occurred between these parts.

When the holding ring 110 is removed from contact with the handle 87 and the latter is swung away from the pitman 20 while pivoting about shaft 86,, the link 92 is pulled to the left, as viewed in the drawings, causing the pin 94 to bear against link 92 at the end 108 of the slot 93 thus pulling cam member 96 out of contact with locking surfaces 80, 81. The shoulders 112, 113 of cam member then bear against the releasing surfaces 73, 74 of the arms 62, 64 forcing them apart and out of engagement with connector 44. With this means the arms are forcibly and easily disconnected from the knife head regardless of the amount of freezing which may have taken place between the various parts due to rust, etc.

It will now be apparent that a single member is provided which, upon a simple lever movement, positively disconnects the pitman from the knife: head and in the operative position insures a tight connection between the pitman and head regardless of any wear that may have taken place.

What is desired to be secured by Letters Patent is:

A releasable pitman connection comprising, in combination a pitman rod having a bifurcated end defining two extending end portions, an arm pivoted to the end of each of said end portions, said arms having opposed surfaces shaped for conforming to and embracing a connector, an elongated cam member slidably mounted be- 4 tween said bifurcated end portions and extending between said arms, cam projections on said member cooperable with cam surfaces on said arms for urging the latter together when said member is slid outwardly, a cam projection on each of said arms cooper-able with cam surfaces on said member for wedging the arms apart and allowing them to swing freely when said member is slid inwardly, and a lever pivoted to said rod and having spring-biased, lost motion means coupling the lever to said member for sliding the latter in and out, said springbiased lost motion means being mounted in protected position between said extending end portions of said rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,291,237 Sturrock Jan. 14, 1919 1,646,464 Sturrock Oct. 25, 1927 1,732,888 Harris et al. Oct. 22, 1929 FOREIGN PATENTS 131,032 Switzerland Apr. 1, 1929 

